Corrosion Of Aluminium In Solutions Research Articles

Experimental and quantum chemical studies of synergistic enhancement of the corrosion inhibition efficiency of ethanol extract of Carica papaya peel for aluminum in solution of HCl

The investigation of ethanol extract of Carica papaya (EECP) as an inhibitor for the corrosion of aluminum in solutions of HCl was facilitated through gravimetric, gasometric, potentiodynamic polarization and quantum chemical methods. The ccorrosion rate for the blank systems was 1.66 × 10−4 mpy but in the presence of various concentrations (0.1 to 0.5 g/dm3) of EECP, it reduces from 1.32 × 10−4 mpy to 0.96 × 10−4 mpy respectively while the inhibition efficiencies ranged from 20.93 to 42.04 % respectively. However, a synergistic combination of various concentrations of the inhibitor with 0.6 M of KBr, KI and KCl enhanced the inhibition efficiency to the following ranges: 75.44 to 87.41 %, 50.20 to 71.89 % and 77.44 to 88.73 % respectively. Potentiodynamic polarization and gasometric results were in good agreement but revealed that ethanol extract of Carica papaya peel acted as cathodic type inhibitor. Calculated activation energies indicated increasing retardation strength with an increase in inhibitor concentration and supported physisorption mechanism. The adsorption of the extract on the aluminum surface was exothermic, spontaneous, and occurred with an increasing degree of orderliness. Freundlich and Temkin's isotherms were most suitable in explaining the adsorption behaviour of the extract. Molecular structures that actively participated in the corrosion inhibition (papain, riboflavin, retinol, niacin and alpha-tocopherol) have been modeled through the calculations of global and local reactivity indices. Molecular simulation studies were also conducted to estimate the interaction between the inhibitor and the metal surface and the results indicated strong involvement of heteroatoms and aromatic rings in the adsorption process. The study concluded, that although the inhibition efficiency of EECP is low, enhancement with potassium halides can give an excellent score towards the management of waste through resource recovery.

Cefuroxime axetil: A commercially available drug as corrosion inhibitor for aluminum in hydrochloric acid solution

Cefuroxime axetil (CA) a pro-drug was tested as corrosion inhibitor for aluminum in hydrochloric acid solution using thermometric, gasometric weight loss and scanning electron microscope (SEM) techniques. Results obtained showed that this compound has good inhibiting properties for aluminum corrosion in acidic medium, with inhibition efficiencies values reaching 89.87 % at 0.5 g / L. It was also found out that the results from weight loss method are highly consistent with those obtained by hydrogen evolution method and gasometric method; and all indicate that inhibitor efficiency increases with increasing inhibitor concentration. Cefuroxime axetil inhibited the corrosion of aluminum in solutions of HCl through the mechanism of physiosorption as confirmed by values of activation energy and free energy of adsorption. The adsorption of the inhibitor was also found to be spontaneous, exothermic and best fitted the Langmuir adsorption model. SEM analysis confirmed the existence of an absorbed protective film on the aluminum surface.

Cefuroxime Axetil: A Commercially Available Pro-Drug as Corrosion Inhibitor for Aluminum in Hydrochloric Acid Solution

Cefuroxime axetil (CA) a pro-drug was tested as corrosion inhibitor for aluminum in hydrochloric acid solution using thermometric, gasometric weight loss and scanning electron microscope (SEM) techniques. Results obtained showed that this compound has good inhibiting properties for aluminum corrosion in acidic medium, with inhibition efficiencies values reaching 89.87 % at 0.5 g / L. It was also found out that the results from weight loss method are highly consistent with those obtained by hydrogen evolution method and gasometric method; and all indicate that inhibitor efficiency increases with increasing inhibitor concentration. Cefuroxime axetil inhibited the corrosion of aluminum in solutions of HCl through the mechanism of physiosorption as confirmed by values of activation energy and free energy of adsorption. The adsorption of the inhibitor was also found to be spontaneous, exothermic and best fitted the Langmuir adsorption model. SEM analysis confirmed the existence of an absorbed protective film on the aluminum surface.

Physicochemical Characterization and Corrosion Inhibition Potential of Ficus benjamina (FB) Gum for Aluminum in 0.1 M HCl

Examination of the physical (colour, odour, pH, solubility in various solvent) and chemical (GCMS and FTIR) characteristics of Ficus benjamina gum revealed that the gum is yellowish in colour, mildly acidic and ionic in nature. Major constituents of the gums were found to be sucrose and d-glucose, which constituted 60.92 % of its chemical constituents while various carboxylic acids (albietic acid (1.00 %); hexadecanoic acid (4.41 %); 9-octadecanoic acid (1.00 %), stearic acid (3.01 %); oleic acid (0.10 %); octadecanoic acid (9.12 %) and 6,13-pentacenequinone (20.43 %) accounted for the remaining constituents. Functional groups identified in the gum were found to be those typical for other carbohydrates. From the knowledge of the chemical structures of compounds that constitutes the gum, the corrosion inhibition potentials of the gum was ascertained and from weight loss analysis, the gum was found to be an active inhibitor against the corrosion of aluminum in solutions of tetraoxosulphate (VI) acid. The gum acted as an adsorption inhibitor that favours the mechanism of chemical adsorption and supported the Frumkin and Dubinin-Radushkevich adsorption models. doi: 10.14456/WJST.2015.94

Theoretical and experimental studies on the corrosion inhibition potentials of some purines for aluminum in 0.1 M HCl

Experimental aspect of the corrosion inhibition potential of adenine (AD), guanine (GU) and, hypoxanthine (HYP) was carried out using weight loss, potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) methods while the theoretical aspect of the work was carried out by calculations of semi-empirical parameters (for AM1, MNDO, CNDO, PM3 and RM1 Hamiltonians), Fukui functions and inhibitor–metal interaction energies. Results obtained from the experimental studies were in good agreement and indicated that adenine (AD), guanine (GU) and hypoxanthine (HYP) are good adsorption inhibitors for the corrosion of aluminum in solutions of HCl. Data obtained from electrochemical experiment revealed that the studied purines functioned by adsorption on the aluminum/HCl interface and inhibited the cathodic half reaction to a greater extent and anodic half reaction to a lesser extent. The adsorption of the purines on the metal surface was found to be exothermic and spontaneous. Deviation of the adsorption characteristics of the studied purines from the Langmuir adsorption model was compensated by the fitness of Flory Huggins and El Awardy et al. adsorption models. Quantum chemical studies revealed that the experimental inhibition efficiencies of the studied purines are functions of some quantum chemical parameters including total energy of the molecules (TE), energy gap (EL–H), electronic energy of the molecule (EE), dipole moment and core–core repulsion energy (CCR). Fukui functions analysis through DFT and MP2 theories indicated slight complications and unphysical results. However, results obtained from calculated Huckel charges, molecular orbital and interaction energies, the adsorption of the inhibitors proceeded through the imine nitrogen (N5) in GU, emanine nitrogen (N7) in AD and the pyridine nitrogen (N5) in HPY.

Commiphora pedunculata gum as a green inhibitor for the corrosion of aluminium alloy in 0.1 M HCl

The effect of Commiphora pedunculata (CP) gum on the inhibition of the corrosion of aluminum alloy AA 3001) in solutions of HCl was investigated using gravimetric and thermometric methods of monitoring corrosion. The results obtained indicated that CP gum is a good adsorption inhibitor for the corrosion of aluminum in solutions of HCl. The inhibition efficiency of CP gum was found to increase with an increase in concentration but to decrease with increasing temperature. The adsorption of CP gum on the surface of aluminum was found to be endothermic, spontaneous and to support the mechanism of physical adsorption. The Langmuir adsorption model has been used to describe the adsorption characteristics of CP gum on aluminum surface.

Physicochemical Study and Corrosion Inhibition Potential of Ficus tricopoda for Aluminium in Acidic Medium

Gas chromatography mass spectrophotometer (GCMS) analysis of Ficus tricopoda gum indicated the presence of 4.75, 56.15, 32.10 and 7.00 % of camphene, sucrose, 2methylene cholestan-3-ol and 7-hexadecenal, respectively. Several stretching and bending vibrations were observed in the Fourier transformed infra-red (FTIR) spectrum of the gum. Physicochemical examinations of the gum revealed that it is pale yellow in colour, mildly acidic, ionic and display characteristics of sour taste. The solubility of the gum in water was found to increase with increase in temperature. Knowledge of the chemical constitution of the gum (hence chemical structures of its constituents) was useful in predicting the corrosion inhibition potential of Ficus tricopoda (FT) gum. Consequently, the gum was found to be a good adsorption inhibitor for the corrosion of aluminum in solution of H 2SO 4. The adsorption of the gum (which, followed first order kinetic) was found to be endothermic at FT gum critical concentration of 0.3 g/L and exothermic at concentrations above the critical limit. The short coming of the Langmuir adsorption model in describing the existent of interaction between the molecules of the gum was complimented by the Frumkin and Dubinin-Radushkevich adsorption models. Calculated values of activation and free energies of activation indicated that the adsorption of Ficus tricopoda gum on Al surface exhibited both physical and chemical adsorption mechanism.

Aromatic acid derivatives as corrosion inhibitors for aluminium in acidic and alkaline solutions

The inhibition of aluminium corrosion in solutions of hydrochloric acid or sodium hydroxide has been studied using weight‐loss and hydrogen evolution methods. Benzoic acid and its derivatives inhibit acidic and alkaline corrosion effectively. The efficiency of inhibitors increases in the order: benzamide < benzaldehyde < acetophenone < benzoic acid < benzophenone (100%). The inhibition efficiency of acid anhydrides follows the sequence: pyromellitic > naphthalic > trimellitic. Inhibition takes place through adsorption by a one‐step process with greater efficiency in alkaline than in acidic methanolic solutions.

The corrosion of aluminium in solutions of sodium fluoride and sodium chloride

The corrosion of 99·997% aluminium by 0·1 N-sodium fluoride and chloride has been examined in the presence of air over the pH range 2—13. When a solution of either salt was saturated with aluminium oxide, corrosion was arrested.Under anaerobic conditions, 0·1 N-sodium fluoride attacked the air-formed oxide film and corrosion was rapid, in contrast no corrosion was observed in 0·1 N-sodium chloride solution.